Speedometer



June 4, 1929.

E. J. VVELSON SPEEDOMETER Filed July 26, 1922 2 Sheets-Sheet E. J. WILSON June 4, 1929.

SPEEDOMETER 2 Sheets- Sheet 2 Filed July 26. 1922 57E/V705? Wfgf/ W l -mass can' be establishedufon given speeds of rotation. VThe improvements .shown in the` Y present application relate vchiefly to a simplif liication ofthe vtorm 'ofthe containerv and yto a y' new arrangement ofthe .partsrwhich permits of.- a morel commercial"designv for lthe .indi, catingmechanism and for the drivingy mechanism Whichrotates the container and. actu- Patented June 4, 1929.

[Unirse sfiarss- ITE EME-RY J. WILSON, OECLEVELANDHEIGHTS, c1110.

s'rEEDolvLE'rER.l

A.appacman fnediuiy 263-1922. Kseriaino..5772730. v

This` invention relates to speedometers of filed lviarchn15,1917;` Patent No.-1,416,083, `filed May 29, 1917 g. and Patent N o. 1,416,084, liledJuneQh'lQlS. l

Iny these prior applications I have shown l tliat,.in a given container for .the liquidhaving certain vof its conining Wallsof. known-1 arbitrary 'shapes andproportions, the ree maining Wall or Wallsv can be so shaped With V `reference tothe ,known factors that predetermined positions ofequilibrium of the liquid ates an odometer, and also resultsin asimpl-ified construction for the mainV frame'vv'hichl supports the entire mechanism.

,The objects of 'thc invention are Arequiredinsoine ofthe prior constructions.

r(2)l To 4extend the length ofthe liquid vorliquid will not have to pass through restricted passages at the low speeds of rotation. (3) To obtain substantially uniform-scale spacing from the Azeropoint of speed up to 'that speed at-Which the compensating or cali# t bration surfaces, described in'v my prior patents, beginto function, by utilizing the action of molecular attraction'inherent in the'wliquid or` existing between the liquid and its supporting `surface.

, (4;) To providea morecommercial con-v struction for the mechanism vwhich translates the, vertical motionof the 'floatjto a rotary motion of the dial. p

; (5) ToI support and drive the container at its upper'end, thereby raisingthe point of aty tachment for the flexible' driving shaft to a` much more desirable-position and permitting the'iuse 0f a simple means for properly Ycharging the instrument While running. u

Further objects of the invention are in partv obvious and in i part Will appear more inde- ,.tail hereafter.

Aspecific embodiment ofthe invention is illustrated r1n vthe accompanying-drawings -in which Fig. 1 is asect-ion through the axis of rotationofthe.container;jFigs. Zand 3are enlarged .cross sect-ionstakenon theflines 2-2 ypart elevation and; part section; Fig: 5 is a fsectionon line 5-4-5 of Fig.4; Figtf is. adey tailoffplate l2fshovvn in- Fig.v 5,:Fig. 7 is an enlargedgdiagrammatic vieivof a.portion of the discharge and central chambers usedr yin,

describing the .operationof gthe device.; and

ifFig.. 8 is a diagrammaticyiew illustratingthe I relative pitch lines oftheteeth -oftheco-operating gearsl and 37'.vv

` In Figure. 8 I; have ,illustrate lation of thelteethV of .co10peratin'g gears't and A37, the dot. and i dash ,line .m indicating the axisy of :thedrivingshaft:35,the dot rand fdasli line' i/indicating 'fthe-aXis of thefinare. lishoivn as-fadaptedto` travel at similar speeds. Owing to 1theadifliculty vvof attemptv ing to show. a true section of theteeth-of gear l 34 in. Fig. 1, yand of theteethof gear-'37 in (1) 'To eliminate certain. accurate settings Figali, the tcethfofthesegears 4inthe'se views are yshown conventionally lasspurI teeth; it isv to be understood7 however',:that'theitrue,pitch tex in thedischarge'chanrberso that the L* da@ piante-e ,gr fait? v line of the teeth ofv thesege'arsl, in thevembodii In the drawings Lindicates the mainframe fof :the instrument. :A rigidpost! 2 isllield fixed .in the frame by nut 8 and islforinedi-to Y' provide an extendedlengthofjournal 4 and enlarged.y lower end 5 to Whichfis rigidly attached the tube. AplugZiitting-.tight in the lower end of the tube, serves` to support 'the cam rodS, theupper portionof which is reduced in diameter ivhe're it passesfcentrally tlirongh a` clearancehole in'vthe post, and `carries a tight fitting spindle 9Yvvhich has a bearingll() in the top end ofthe post. A vdial 11 is adjustably mounted on the uppcrj end ofthe spindle[andfclamped theretog-by lock nut 12.l The tube 6 forms a .centralzjchamber 123 containing a non-rotatable column lofniercuryfon Whichrcsts afloat Which is adapt, cd to move up-Vandfdown` inthe vtube as mer-l curyflows to andnfrom the central chamber. rEhe float carries at its lovver end.: a'plate 15 )with radial; projections E16'. which. :slide in icc llO

straight vertical grooves 17 machined on the inside of the tube, and at its upper end a tight fitting pin 18 and adjusting screw-19, said pin and screw having their inner ends conical the surface 47 lying at the periphery of the and adapted to slide along'V-shaped helical grooves 20 in the cam rod 8. The whole ar rangement is such that the dial 11 rotates through equal angles as the float moves vertically through equal distances. In this ar-` rangement it is to be noted that clearance spaces 21 and 22 (Fig. 2) are `provided between the float and tube, and between the float and the cam rod, and that the upper end Vof thefloat is guided entirely by the pins 18 and 19 working in the cam grooves, while the lower end of the float is guided entirelyfby d the projections 16 working in the tube grooves Y* ing on journal 4 and is provided at its lowerV end` with a'ball bearing 32 supported on thev 17, sothat the float can adjust itself to inaccuraciesiof alignment which may exist between the cam rod and tube.

outer cylindrical surface 25 (radius='Rl) of the tube, form a discharge chamber 26 which "is in constant liquid communication with the central chamber 13 through vertical and radial grooves 27 and 28 formed in the body 23, and through the axial hole 29 and radial holes 30 formed inthe bottom plug 7. Cap 24 carries a tight fitting insert 31 which has a bearenlarged end 5 of therpost 2, so that the rotating receptacle is'centered upon and entirelyVr supported by the post, and is rotatable'about the fixed tube 6. Theinsert 31 extends upward from cap 24 into a pocket 33 of frame l, and forms a spiral toothed gear 34 at its upper end. yAn inclined driving shaft 35 (Fig. 4), supported'in bearings 36 of frame 1, carries another spiral toothed gear 37 which mesheswith gear 34, and a worm 38 which meshes with worm gear 39 having its journals 40 and 41 supported respectively in frame 1 and cover plate 42 attached to said frame by .screws 43.' Parts 38 to 44, together with parts i of other structures shown, pertain more pain.l ticularly to an odometer mechanism which may be employed in connection with the present invention.

In L* igure 8 I have illustrated the pitch relation of the teeth of co-operating gears 34 Vand37, theV dot and dash line m indicatingA the axis of the driving shaft 35, the dot and dash line y indicating the axis of the insert 31l by which gear 34 is carried), and cap 24; in fact, the line y indicates generally the axis of rotation of the mercury-carrying 1 parts of the speedometer. The two gears are shown as adapted to travel at similarspeeds. Owing to the difficulty of attempting to show a true section of the teeth of gear 34 in Fig. 1, and of the teeth of gear 37 in Fig. 4, the teet of these gears in these views are shown conventionally as spur teeth; it is to be understood, however, that the true pitch line of the teeth of these gears, in the embodiment shown in the drawings, is illustrated in Fig. 8.

In this invention the proper formation of `on the dial, clear down to the Zeropoint of speed, will correctly indicate these low speeds of rotation. This surface is in effect another compensating surface. It would be difficult and probably impossible to derive exact mathematical formulae for the shape of this surface, even though the laws of molecular attraction were well known, but it is quite possible to determine empirically this shape with sufiicient accuracy for all practical purposes since it functions only at the very low speeds.

It is well known that mercury resting'on a flat horizontal surface tends to` remain col lected into a single mass of considerable depth with its edges rounded under to the point of contact with the supporting surface. If the supporting surface be slightly -dished to a lconcave spherical form, the mercury mass will assume the form of a round flattened disc. If thisfdisc is rotated slowly about a vertical axis the centrifugal force'of the mercury tending to spread it out acts against itsinherent molecular attraction which tends to keep'itV from so spreading. The point at which balance takes place for any particular speed dependsfon the slope of the supporting surface. By varying this slope the desired predetermined positionsgof equilibrium of the mercury mass can be established. It is of course understoodl that the tendency of the top surface of the mercury Ato form a vertex exists at all speeds.

Referring to the diagrammaticview Fig. 7, the zero level of thelmercury when the instrument is at rest is .at the line 00p-m, its outer peripheral edge assuming the curved form as noted above and as indicated at 48, due to `molecular attraction; so that anopen space 49 is formed at theperiphery lof the discharge chamber below the Zero levelA of the mercury. This space 49 is bounded by the surfaces 47and 50n of the receptacle, and the mercury surface48; andits volume must necessarily be equal to the volume of liquid bounded by the line the vortex curve al, the surface 50l'of the receptacle, and that portion of the mercury surface 48 which lies above the vortex curve f1/1. An air duct 46, Fig. 1, uniting the space 49 to the space in the discharge chamber above the Zero line, is needed to permit free movement of air to and from space 49 to prevent pocketing of air or the formation of a vacuum therein. During the period whenV such space 49 is actually present, air can pass between it and the-portion of the chamber above the Vliquid level; with the elimination of the space by the pres- ,ence of liquid therein, there is no further need for'the activity of the'duct and itbecomes closedby'the liquid until the level of `position are noted.v lf the movement of the float cori'jespondmgto anincrease of speedv da is less than the desired value ZcZa, the slope of that portion'of the curve 47 just ,pased over by the inercuryis too steep; if the movement is greater than Ida the said slope is not great y enough. Z=the assigned uniform movement ofthe float for one R. P. M. change of speed. .By using a suitable material such as paraltin as a lining for this part of the experimental container, the derivation of the surface 47 is facilitated. lt is of course understood that when the proper shape of the surface 47 is once determined it can be permanently 'incorporated 'in the die used for v'moulding the body 23, so that this feature ofthe construction adds nothing` to the manufacturing cost of future instruments.

`The primary object of the surface 47 is tivo-fold :Fii'st,`-to produce a free space in the discharge chamber beloivthe level of the liq v y zuid When the instrument is at rest, into which space the mercury can flow when the instrument starts to rotate, and from which the mercury can be drawn by molecular attrac-n tion as the speed of rotation approaches zero;

and second, to elevate tiie float to that. point from which its movement isproportionalto thespeed of rotation, namely, theline iix,

' so that the scale spacing from O to say 5 miles per hour will be of the same length as other 5-mile portions of the scale. This Will be clearly understood by reference toFigs. 16 and l7 of my Patent Number 1,416,084 in which no such surface as 47 exists, and consequently the Zero level of the mercury-must come below theline .ov- 00, Withthe result that Y lthe scalefrom O to 5 is much, 'less than it is from 5 to 10. The secondary object of the surface 4:7, namely,'the obtaining of an eX actly uniform scale spacing over this low range of speed from 0 to 5,'is simply a further refinement of operation.

The operation of the instrument is as folloivs (l) As the speed increases The outer edgeS of the mercuryrin the discharge chamber moves outward and up-V ivard along the surface 47fiint1l`the 'top free surface of the mercury massfassumes the position indicated by the .vortex curve nl; The top surface rofthe mercury in v'the central chamber remains al plane surface'` tangenty at fthe `vertex ofthe changing vortexfinfthe discharge chamber, and moves 'downward through'the `distance Hllnl. Throughout this rangeof action thefloat moves through equal I'distances 'for equal changes :of: speed,

due to the functioning of the -surface47.

(2) As the speed increases from iV-a, to

fn=maximumsrThe upper limit of the vortex curve in ithe di-scliarge chamber travels *inward and Aupward along the calibration surface 50; Ythe lower `limit `of the vortex curve travels first downward, then upward, along theV cylindrical '-basesurface 25 (radiuslRQfand the `topv surfaceof the mercury in the central `chamber continueszto descend through equal distances for ,equal changes of speed, dfue to the functioning of the calibration surface as fully described in i my-priorpatents. Inllig. l an intermediate position of-thefiioatis shoivn bydottedlines Aat 14 `and ythe vortexlfor the` speed corre-V `spondingvtothis position is shown at The'genei-al' equations forthe coordinates R and m of the curve '-for this calibration surface 50 are the sameas those 'given on page 5, lines f50e55, lof my Patent Nth-1,416,084,

'for curve 57described-therein. The assigned values of the constantsfRl, ZA and' p1' used 'for equations referred to are `These equations show` that the curve 50 is tangent-,to the Zero line at iniiiiity. Fig.

7 shows that'it approaches very closely to the line at the finite distancelo, the value of x when R=R0being equal to- -,.004t for the proportions shown inthe drawingsthe "curve 57 arehoWever diiferentffrom those ,used for jthe present curve50. vThe general.

negative sign indicating that this point ofthe curvenis ibeloiv the linea-rc; and the maximum negativevalue of a1 is *.015 correspondiiigto It L7Ll0. face of the mercury were unbroken by the insertion of the fixed tube which prevents lf the vortex sur,

the mercuryWithin itfrom rotating, the curve S50 would become a straight line coinciding with l The valueof n, referredvto 4above is found from equation (l) by setting R=R0 and solving forln=7ir p i li'ointhe above itiwill loe-understood that I 'have provided an improved Yform'for the..

rotatingreceptaclefor the mercury, in that the restricted passages inthe discharge kchambers shoivnuin' my `prior rapplications have been entirely eliminated, therebyfpermitting the top :surface of the mercuryiin' said chain'- ber to form its Ytrue vortex `more readily. Furthermore, a decided advantage is gained in point of manufacture since the accurate setting of a horizontal base surface with reference to its derived calibration surface is dispensed with; and a surface Valready existingin the structure is used as a base surface, namely, the outside surface of the fixed tube 6, which does not have to be set to any particular vertical position.

The working parts :of the instrument are suitably enclosed in a two-part casing coinprising upper half 94 and lower half 95 with `its tubular extension 96. Both parts are attached by a number' of screws 97 to the U- sliaped flange 98 forming a part of frame 1. The usual bezel ring 99, glass .100 and face plate y101 through which the desired portions of the speed scale and odometer are visible,

arevof usual construction.

In charging and testing the speed indicator' it is desirable to have an easy means of supplying and regulating the amount of mercury f required for accurate registration ofthe speeds.

Ifv the receptacle is suitably connected to a fixed source of supply this operation can be performed while the receptacle is rotating. Such a connection is indicated at the bottom endV of the body 23 and comprises simply a plug 103 whichis screwed into the body at the axis of rotation and is adapted f to properly fit ,and rotate about a suitable able spanner wrench.

supply nozzle inserted'in the aXial vhole 104 of the plug. An eccentric hole 105, located in the lower wallof said body, establishes liquid communication between the nozzle and the. r receptacle Vwhen the plugr isslightly withdrawn from its seat 106, by means of a suit- When vthe proper amount of mercury is introduced into the reo ceptacle, thesupply from the nozzle is first shut off. then the rotation of the instrument is stopped, the plug screwedvdown tight on its seat, thenozzle withdrawn and the plug perupon rotation, said discharge chamber hav-A ing anormal zero level of the liquid when the instrument is at rest, said discharge chamber including as a portion of its liquid confining walls a surface'lying below the plane of such normal zero level and adapted to be traversed by the liquid during movement of the latter when the instrument is in speed-responsive service, the position of said surface being such that a predetermined cross-sectionalarea of the chamber between such surface and such plane will be maintained free from the liquid bymolecular attraction of the liquid when the instrument is at rest, and contain liquid during speed-responsive movements `of the instrument. y n

2. An indicator as in claim 1, characterized in that the value of the free cross-sectional area of the chamber between such surface and plane is varied in a decreasing direction as the speed is increased.

3. An indicator as in claim 1, characterized in that the value of the free cross-sectional area of the chamber between such surface and plane-is variedin a decreasing direction as the speed is increased, with the cross-sectional area eliminated in presence of a speed-value equal to and beyond a definite speed value in suchincreasingdirection. v

4. .An indicator as in claim 1, characterized iii that the value of `such predetermined cross-sectional area is reduced to vzero in response to a speed value of a predetermined ainount and maintained insuch con-v dition during periods when the speedvalue is equal to or greater than thatv of such predetermined amount. l

5. An indicator as in claim 1, characterized iii that the value of such pnedetermined` cross-sectional area is reduced to zero in response to a speed value of a predetermined amount and maintained in such condition duringperiods when the speed value is equal to or greater than that of such predetermined amount, the value of such cross-sectional area being varied in an increasing direction by molecular attraction of the liquid as the speed is decreased fi'om such predetermined speed value. v

6. An indicator as in claimr 1, characterized in that such lower surface is shaped relative to its opposing liquid-confining wallof that portion of the out-er chamber included within the zone of such predetermined crosssectional area, that the space included within suchv area will receive such increments of the liquid when rotated as will make the movement of the liquid in the inner chamber proportional to Jthe speed` of rotation, due to the conditions of molecular attraction present within the outer chamber.Y Y

7. In speed indicators, wherein a` confined liquid mass is subjected to centrifugal action to produce characteristics of a vortex, wherein the carrier for the liquid mass is formed to provide inner and outer chambers in permanent communication and with each chamber having a free liquid surface of the mass, the free surfaces being in permanent connection through the body of the mass, and wherein the indications aremade responsive to the changes in position of the free liquid surface of the mass of the inner chamber, means operative to establish deiinite positions soV ioo

of equilibrium of the mass at definite speeds of rotation in presence of mass increment flow produced by variations in speed, said means including aA succession of faces of the outer chamber positioned to be traversed successively byV free liquid surfaces operating in said chamber, one of said faces lying belowy the plane of the normal Zero level of the liquid Within suoli outer chamber.

8. An indicator as in claim 7, characterized in that other of the faces traversed by a free liquid surface operating in the outer chamber are located above such normal Zero level of the liquid Within the chamber.

9. In a centrifugal speed indicator Wherein the speed is evidenced by a rotatable indicator made responsive to the vertical movement of said liquid, means for translating the said vertical movement of the liquid to said rotatable movement of the indicator, said means comprising a iloat supported by said liquid, a rotatable rodcarrying said indicator, a iixed member supporting said rod,

and means for causing float movements to be translated into rotational movements of the rod, said latter means including spaced-apart elements carried by the float and adapted to traverse a vertical groove of the iXed member and a helical groove of therod respectively, said elements including Van adjusting screw having a conical exposed end co-operative with a groove, such groove being V- shape in cross-section to be complemental to such -conical end, said screw being located materially above the lower face, of the float,

the element which co-operates with the 'EMERY J; WILSON. 

